The present invention relates to active matrix type light valve devices using monocrystalline semiconductor layers as an active region, stereoscopic image display devices capable of observing an image from light valve devices provided on both eyes to obtain stereoscopic vision, and image projectors composed of a light source section, the light valve device, and a projection optical system.
Conventionally, the light valve devices of compact type image display devices used in view finders of the 8 mm video cameras are made by depositing polycrystal or amorphous silicon thin films on transparent electrically insulating substrates by vapor depositing or vapor phase epitaxy to form an individual-pixel switching element group and a X-Y electrode driving circuit group for driving such switching element group by the thin film transistors.
First, the conventional active matrix type liquid crystal display device is described referring to FIG. 40 for its general configuration. In the image display device of this kind, one quartz glass substrate 1001 and the other glass substrate 1012 are oppositely arranged each other and a liquid crystal layer 1016 is sealed between the substrates. On a main surface of the quartz glass substrate 1001 is formed a film of a silicon polycrystal semiconductor layer 1002P, which constitutes an active region. A pixel array section 1017 and a peripheral circuit section are integrally formed on an inside surface of the quartz glass substrate 1001. The peripheral circuit section includes an X axis driving circuit 1006 and a Y driving circuit 1008. Matrix driving electrodes 1005 are formed on the pixel array section 1017 as orthogonally intersecting in the X axis direction and Y axis direction, and pixel electrodes 1010 are formed on intersecting points thereof. Switching elements 1009 are arranged corresponding to individual pixel electrodes 1010. The switching elements 1009 are composed of the thin film transistors (TFT) having the silicon polycrystal semiconductor layer 1002P as an active region. Drain electrodes thereof are connected to the corresponding pixel electrodes 1010, source electrodes thereof are electrically connected to the corresponding X axis matrix driving electrodes 1005, and gate electrodes thereof are electrically connected to the corresponding Y axis matrix driving electrode 1005. The Y axis driving circuit 1008 selectively scans the matrix driving electrodes 1005 of the Y axis direction in lineal sequence. The x axis driving circuit 1006 is electrically connected to the matrix driving electrodes 1005 of the X axis direction and feeds display signals to the pixel electrodes 1010 through the selected switching elements 1009. A polarizer 1011 is bonded on an outer surface of the quartz glass substrate 1001.
A common electrodes 1014 are entirely formed on an inner surface of the other glass substrate 1012. A color filter with three original colors RGB is simultaneously formed for color display. A polarizer 1013 is bonded on outer surface of the glass substrate 1012. The substrate 1012 on the upper side is bonded to the quartz glass substrate 1001 on the down side by seal agent 1015. The seal agent 1015 is supplied along a seal region 1018 shown by dotted lines. The seal region 1018 is provided to embrace the pixel array section 1017, the peripheral circuit section composed of the X driving circuit 1006 and Y driving circuit 1008 are positioned outside the seal region 1018.
These amorphous silicon thin film and polycrystal silicon thin film are easily deposited on the glass substrate by chemical vapor phase epitaxy or like procedures, thus they are suitable for producing a an active matrix type liquid crystal display device having relatively larger display. The transistor elements formed into the amorphous silicon thin film or the polycrystal silicon thin film are generally of a field effect insulating gate type. Displays of approximately 3 inches to 10 inches are included in the active matrix type liquid crystal display devices using the amorphous silicon thin film which are commercially manufactured these days. The amorphous silicon thin film can be formed at a low temperature equal to or less than 350xc2x0 C. and therefore it is suitable for a large-area liquid crystal panel. The active matrix type liquid crystal display device using the polycrystal silicon thin film is now produced which includes display of a picture size approximately 2 inches in the market.
However, the conventional active matrix type liquid crystal display device using the amorphous silicon thin film or the polycrystal silicon thin film is suitable for direct-view type display devices using relatively larger displays, however it is not always suitable for miniaturizing the devices and high density planning of the pixels. Recently, microminiature type display devices or light valve devices with a microminiature device structure and high density pixel formation are now increasingly in strong demand, other than the direct-view type display device. Such microminiature type light valve device is, for example, used as a primary image forming display of the image projector, and can be applied for the high-definition type television of the projection type. The application of the technique in producing fine semiconductors provides the microminiature type light valve device having a pixel size in the order of 10 xcexcm and with an entire size of about several centimeters.
Some secondary problems arise in using the active matrix type liquid crystal display device as a light valve device of the projector. The drawbacks in the liquid crystal display device include damage of its light valve function due to temperature rise. In the projector, the light source intensively lights the transmission type liquid crystal display device to project the transmitted light forwardly through an enlargement optical system. Such intensive light from the light source is absorbed in the liquid crystal display device to cause temperature rise, thus if the temperature exceeds a critical point, the liquid crystal phase itself turns to be liquid and not liquid crystal any more.
The use of the active matrix type liquid crystal display device as a light valve device provides a drawback of a relatively lower brightness of the projected image. The pixel image accounts for a relatively too small ratio of space of the entire liquid crystal panel surface to provide a sufficient opening ratio. This prevents a brightness of the projecting image from increasing because of low utilization efficiency of the light. In addition, the polarizer which absorbs light is generally bonded on the liquid crystal panel, therefore the transmitted light amount decreases. Therefore, the use of the liquid crystal panel as a light valve device disadvantageously causes a lower utilization-efficiency of the light.
Conventionally, the light source is used only for lighting the light valve device, and is not intended for other utilizations. The projector requires an intensive light source capable of large amount of energy radiation, however such energy itself is almost lost uselessly. Thus, a problem arises that larger is given the projector power supply.
Using parallax of both eyes has conventionally been proposed to view stereoscopicaly image. For examples, (1) images for the left eye and right eye are separately picked up using two cameras, and projected alternatively on a monitor or a screen by switching from one image to the other, a liquid crystal shutter device is used to alternatively turn ON or OFF the left eye and the right eye in synchronization with the switching period of the projected images, thus the left eye watches the image prepared for the left eye and right eye watches the image prepared for the right eye to view stereoscopically image, and (2) image display elements are arranged separately in front of both eyes to display different images for each of the both eyes, thus a method of stereoscopic view is provided.
However, the conventional amporphous or polycrystal silicon thin film hardly operates at a high speed because of its lower driving current due to its monocrystalline material, it is impossible to form a sub-micron order of transistor elements even by applying the microminiature semiconductor technique. For example, a mobility of the amorphous silicon thin film is about 1 cm2/Vsec, this prevents the peripheral circuit requiring a high speed operation from forming on the same substrate. In using the polycrystal silicon thin film, crystal particles have each size of approximately several xcexcm to correspondingly limit the fine planning process for the transistor elements. Accordingly, in the conventional compact size image display devices using the polycrystal or amorphous silicon thin films, it is extremely difficult to realize integration density and high speed operation similar to those of the ordinary semiconductor integrated circuit elements.
The transmission type panels such as view finders require the light source elements, but the active elements of these driving circuits need to be composed of discrete parts because of requirements for a high withstand voltage and large current driving. Hence, it is difficult to produce, an integrated unit as a display device containing the light source elements which is a problem in realizing compact size and convenience on utilization.
There are limitations such that, in view of an electrical performance, it is impossible to assemble both the control circuit for supplying timing signals to the peripheral circuit section (for example, driving circuit) necessitating the high speed operation and the driving circuit for the light source elements together on one substrate, while in view of a integration density, the increase in size prevents the other peripheral circuits from incorporating therein. For this reason, in the present situation, it is impossible to assemble the peripheral circuit section, other than the pixel array section and the driving circuit group thereof on one substrate.
In view of the conventional problems mentioned above, the present invention is display elements for a compact size image display device in which a switching element group for selectively supplying electricity to the pixel and a highly integrated peripheral circuit capable of operating with high speed are formed on one substrate, and the peripheral circuit includes a driving circuit capable of driving the light source elements with a high withstand voltage and large current. The present invention provides an improved reinforced structure of the light valve device with high reliability, high utility convenience, microstructure, high density and high accuracy by integrating the light source elements and the display elements into a unitary structure. In particular, another object is to provide a packaging construction of a light valve device with a high grade in compact size, solidity, easy handing, reliability, light shielding, cooling, and assembling. Further another object is to improve an image reproducing quality by preventing attenuation of the display signals. Still another object is to improve image to be highly fine by saving display data transfer speed in respect of circuit and increasing the number of matrix driving electrode groups correspondingly. In addition, further another object is to provide a fine and highly accurate display devices suitable for the view finders and the like by reducing of outer sizes of the flat panels.
In the methods of stereoscopic view described in the prior art, method (1) has a problem in tiring the eyes due to a flickering image method (2) constitutes display elements using the transparent substrate formed of the pixel array section and the driving circuit on the polycrystal silicon thin film. In view of an electrical performance, it is impossible to assemble both the control circuit for supplying timing signals to the peripheral circuit section (for example, the driving circuit) necessitating the high speed operation, and the driving circuit for the light source elements together on the same substrate, while in view of an integration density, the increase in size prevents the other peripheral circuits from incorporating therein. For this reason, in the present situation, it is impossible to assemble the peripheral circuit section other than the pixel array section and the driving circuit group thereof on one substrate. Hence, the peripheral circuits other than the driving circuits require to be formed on the external circuits. Moreover, image data generated by the external circuits, and timing signals both must be connected by wires, where inconvenience arises in handling and operating. A space is required for disposing light source elements for irradiating the display elements and the pixel array section of the display elements from the back-side thereof, this causes a problem of thinner construction.
To solve the problems hereinbefore described, the present invention comprises at least a transparent electrically insulating substrate and a semiconductor monocrystalline thin film regulating a peripheral circuit area arranged in at least a part of the substrate surface. A pixel array area is provided in adjacent with the peripheral circuit area, A pixel electrode group and a switching element group for selectively supplying electricity to the each pixel electrode is provided. The switching element group is driven by X and Y driving circuits. There are similarly included a control circuit for supplying timing signals to the X and Y driving circuits, a display data generating circuit for generating display data, and a receiving circuit for receiving image data through radio communication. These peripheral circuit and driving circuit switching element group are integratedly formed, for example, using a very-large-scale integrated circuit (VLSI) manufacturing technique.
To produce the compact type image display device of such structure, semiconductor monocrystal, for example, a high quality of silicon monocrystalline wafer ordinarily used for forming VLSI, is bonded on the transparent electrically insulating substrate, this wafer is mechanically or chemically abraded to produce a semiconductor thin film on an entire surface of the substrate. The semiconductor monocrystalline thin film is selectively processed by VLSI producing technique to form a first transparent substrate which is formed of switching elements, X and Y driving circuits, a control circuit and a light source element driving circuit for driving light source elements. Next, the second transparent substrate composed of the transparent electrically insulating substrate arranged with the common electrode is provided in the region opposed to the pixel array group formed on the first transparent substrate, the electrooptic material is sealed into a gap between the first and second substrates to constitute the display elements. Electro-luminescence elements (EL element), fluorescence lamp elements (FL element) and the like as a light source element of the display elements are disposed on the backside of the display elements to mount them inside of a tightly sealed unit structure integrally.
According to one embodiment of the present invention, the display data generating circuit includes a RGB conversion circuit for converting composite video signals into RGB display signals and a synchronous separation circuit for separating synchronizing signals from the composite video signals. The control circuit generates the timing signals depending on the synchronizing signals. According the other embodiment, the driving circuit section includes two sets of X driving circuits and one set of Y driving circuits. The two set of X driving circuits are arranged separately upper and lower relative to the pixel array section, and operated parallely each other in accordance with the predetermined timing signals. On the other hand, the Y driving circuit, control circuit, and display data generating circuit are arranged separately on left and right to the pixel array section. According to further another embodiment of the invention, the display data generating circuit includes an A/D converter circuit for converting analog display signals temporarily into digital display data. The driving circuit section includes a D/A converter circuit for re-converting the digital display data into the analog display signals. According to still another embodiment the pair of substrates are bonded each other by a seal region provided along the peripheral portion of the substrates. This seal region is arranged to overlap lively with the peripheral circuit section including the driving circuit section, the control circuit, the display data generating circuit.
The present invention is to provide an improved structure of a light valve device with a microminiature size, high density and high accuracy. Particularly, an object is to provide the mount structure of the light valve device superior in size, solidity, handling, reliability, light shielding, cooling, and assembling and like factors. To achieve such objects, an IC package type monocrystalline semiconductor light valve device has been invented. The light valve device according to the invention has an IC package structure in which light valve cells, connector terminals, and package members are formed into a unitary shape. The package members embrace the light valve cells to enhance them physically, and possess a structured portion for shielding a window section matching to the pixel array section and the peripheral circuit section. The connector terminals have one end electrically connected to the peripheral circuit section of the light valve cells and the other end protruding from the package member.
The package member may preferably be made of black molded resin product, otherwise the package member may be formed of ceramic mold product. The window section of the package member is attached in unitary shape with a protecting glass member. According to one embodiment of the present invention, the package member has the same thickness as that of the light valve cell. The package member is provided on its external surface with heat radiating fins, or the window of package member is attached with an infrared ray filter for cutting heat ray. The infrared ray filter is laminated sometimes on the polarizer disposed apart from the light valve cell. According to another embodiment, the package member has a through hole to be a flow path of coolant. For a particular embodiment, the package member is provided with a recess portion for detachably holding the light valve cell.
The connector terminals are disposed in parallel with the light valve cell and in a manner of protruding from the lateral end surface of the package member. Otherwise, the connector terminals may preferably be arranged in orthogonal to the light valve cell and in a manner of protruding from the main surface of the package member.
An object of the present invention is to provide a projector light valve device having a high density and high accuracy with a compact size. In addition, an object is to provide a cooling structure effectively suppressing temperature rise of the light valve device. Another object is to improve a lightness of the projecting images. Further, an object is to provide a possibility of effectively utilizing light source energy. To achieve the objects, various counter measures are taken as undermentioned. The projector according to the invention includes as a basic constituent element a light source section, a light valve device, and a projection optical system. The light valve device includes a pair of transparent substrates disposed opposingly each other, and an electrooptic material arranged between the substrates. On one transparent substrate, a pixel array section and a peripheral circuit section for driving that section are provided. The other transparent substrate is provided thereon with a counter electrode. As a feature of the present invention, the peripheral circuit section is integratedly formed on the monocrystalline semiconductor layer provided on the one transparent substrate.
Preferably, the pixel array section includes a pixel electrode group arranged in matrix shape and a switching element group for selectively power supplying to individual pixel electrodes, and at least, one of the transparent substrates includes a light-reflective shield film for shielding individual switching elements from incident light. Preferably, a solar cell is integrally formed on the semiconductor layer to photoelectrically convert incident light and to directly supply a power supply voltage to the peripheral circuit section. More preferably, the light valve device includes a micro-lens array to converge the incident light and to selectively light the pixel electrode group contained in the pixel array section. The micro-lens array is adhered on one of the transparent substrate through a transparent adhesion layer having a smaller refractive index compared there with. In addition, the light valve device preferably includes a cooling means, which concretely is composed of a container for containing the light valve device, and provided with an inlet for introducing compressed gas and an outlet for discharging decompressed gas to cool the device by means of adiabatic expansion. Or, the cooling means includes a fan for sending cooling gas to the light valve device. Or, the cooling means is composed of the container for containing the light valve device and a cooling system connected to the container and for supplying cooling gas. The cooling system is provided with an automatic temperature control arrangement. A supply port and a discharge port of the cooling system are provided together on lateral surface of the container.
In the display device as constructed above, a substrate with a double layered structure composed of an insulating substrate and a semiconductor monocrystalline thin film formed thereon is used and the semiconductor monocrystalline thin film layer has the same quality as that of a wafer formed of semiconductor monocrystalline bulk. Accordingly, the VLSI manufacturing technique is used to integrate switching elements, and a driving circuit for driving the pixels and peripheral circuits such as a receiving circuit, at ordinary electric performance with a high density, high withstand voltage, and large current driving. In addition, the display elements and the light source elements are made unitary to produce a display device which constitutes a stereoscopic vision display device for binocular, thus a wireless stereoscopic view image display device of a compact size can be provide.
Further in this construction, a video signal processing function and the like can be added to a flat panel device and is suitable for a view finder and the like of the video cameras. The peripheral circuit employs a digital type, and not the conventional analog type. Thus, the analog video signals are converted into the digital display data for data processing or data transfer, thereafter at a final stage, the digital display data is re-converted into the analog display signals to drive the pixel array section, hence an excellent image reproducibility is secured without attenuation of display signals. The VLSI manufacturing technique is used to parallelly operate using the driving circuit as a split structure and to decrease driving frequency, thus, correspondingly the number of matrix driving electrodes can be increased to achieve highly accurate images. Moreover, the peripheral circuit section is disposed on periphery of the pixel array section in the center and the seal region is arranged so as to overlay the peripheral circuit section, there can be obtained a highly integrated multi-functional compact image display device in which a center of the display picture is substantially coincident with the center of the flat panel.
According to the present invention, the light valve cell is constituted using the monocrystalline semiconductor layer to integrate and form the peripheral circuit section and the pixel array section into a unitary shape with a high density, thus a microminiature type highly precise light valve cell can be obtained. The light valve cell, the connector terminals, and the package member are integrally formed to provide a IC package construction. Therefore, as in the ordinary IC device, it is extremely easy to handle and is readily assembled into the circuit substrate and the like. In addition, a high grade of solidity, compact size, and reliability are provided because of mold products, and moreover, a shielding effect and cooling effect are given depending on requirement to be suitable for the projector.
According to the invention, the transparent substrate having the monocrystal semiconductor layer is used to form integration of the projector-light valve device. The peripheral circuit section for driving the pixel array section is integratedly formed on the monocrystalline semiconductor layer. It is of course possible to form also the pixel array section on the monocrystal semiconductor layer. The monocrystalline semiconductor layer has a high uniformity of crystal and is thermally stable, thus processing at a high temperature can freely be performed to produce the fine structured monocrystalline transistor element, simultaneously since it has a larger carrier mobility compared to the polycrystal semiconductor layer or amorphous semiconductor layer, the transistor element with a high speed response can be obtained. Therefore, compared to the conventional example, the projector light valve device with a compact size, high performance, high density, and high accuracy is produced. The video signal processing circuit and the like in addition to the driving circuit can be added to the peripheral circuit section according to the circumstances.
In addition to the foregoing basic operation, various devices are intended. For example, the light reflection shielding film is formed on the transparent substrate for shielding the individual switching elements from the incident light. The light reflection shielding film not only prevents light leakage of switching elements but also suppresses temperature rise of the light valve device because of reflecting the incident light. The solar cell is integrally formed on the monocrystalline semiconductor layer to enable a self-sufficent power supply voltage and to intend effective energy utilization for the peripheral circuit section. The light valve device contains the micro-lens array, and only the pixel electrode portion is selectively lighted to improve a utilization efficiency of the light from the light source. The light valve device includes the cooling means to effectively suppress temperature rise.